Simple theory of input couplers for gyroklystron amplifiers

This paper formulates and evaluates simple approaches to the input-wave coupling problem in the Naval Research Laboratory (NRL) 91 GHz gyroklystron amplifier. It looks at the hole between the input waveguide and coaxial cavity, as well as the coupling holes between the coaxial cavity and main cavity as a simple dipole. Direct comparisons are made between the dipole theory and simulations using the Maxwell's equations solver high frequency structural simulator (HFSS). The results are in reasonable agreement. Where the theory lacks accuracy as compared to modern field solvers, it may gain in simplicity, speed of operation (both human time and computer time) and analytic insight.